1. Technical Field
This invention relates generally to seam tape, and more specifically relates to a seam tape having rigid brace members disposed transversely to the longitudinal axis of the tape to thereby reinforce the tape, and hence carpet seams, against buckling.
2. Background Information
A longstanding problem in the carpet laying service is the tendency of adjoining carpets to rise along the length of their common seam. This unsightly buckling is caused by the stresses appearing at the seam, and is a source of frequent consumer complaints.
The most widely used means for attempting to retain the abutting carpet edges in a flat disposition is the well known heat bond seam tape. The tape is a composite structure of three primary elements. Essentially, an open mesh reinforcing means, or webbing, is held in sandwiched relation between a strip of paper and a strip of thermoplastic adhesive. The purpose of the tape is to secure the seam, i.e., to prevent the seam from separating responsive to oppositely directed stretching forces imparted to the abutting carpets. It is the weakness of the open mesh, or webbing, which allows the carpets to buckle, or lift, at the seam.
Another drawback of prior art hot melt seaming tape is the tendency for the webbing to separate from the paper upon which it is adhesively mounted when the heat seaming iron is used to melt the layer of thermoplastic adhesive. This phenomenon, known in the trade as web drag, severely weakens the tape and contributes to the lifting of the adjoining carpets at the seam.
A further seaming tape of the prior art is known as pin tape, and includes a plurality of metallic bracing members disposed in sandwiched relation to the paper base and the webbing. The braces have upstanding teeth with which to grab the carpet backing.
U.S. Pat. No. 4,935,280 discloses a prior art seaming tape having reinforcing filaments of high-strength yarn such as fiberglass, synthetic fibers or metal wire woven into the mesh backing of the tape. U.S. Pat. No. 4,565,728 also discloses another type of seaming tape having metal wires embedded therein for heating in order to melt the adjacent adhesive, as well as reinforcing cords of fiberglass or the like. U.S. Pat. No. 4,416,713 shows another prior art carpet seaming tape which includes reinforcing filaments formed of rayon or glass fibers which extend transversely across the width of the tapes.
Although prior art carpet seaming tapes such as those discussed above all contain reinforcements, they are in fiber form. Although such fibers may provide reinforcing to the mesh, it does not provide the required reinforcement to prevent buckling or uplifting of the carpet edges at a seam.
There is a need in the carpet laying service for a seaming tape that provides lift-free seams and that is free of web drag problems, but the prior art shows no such tape.